Supporting Information: Shrink-wrap Vesicles
S.M. Fujikawa, I.A. Chen, J.W. Szostak
Figure S1.
Standard curve of donor fluorescence vs. probe density for the FRET assay (F/F0 = donor
fluorescence/ donor fluorescence in 1% Triton X-100). The solid line shows a fitted curve
(y = -0.203*ln(x) - 0.025).
Figure S2.
Standard curve of self-quenching of calcein vs. concentration (Fves/F0ves = calcein
fluorescence/ calcein fluorescence in 1% Triton X-100). The solid line shows a fitted
curve (y = 0.00052*x2 - 0.036*x + 1.12).
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Figure S3.
Release of calcein during and after shrinking of MA vesicles (a representative trial is
shown). Although vesicle size has equilibrated by ~500 minutes (see Fig. 1A), calcein
continues to be released slowly. The solid line shows a single exponential decay curve fit
for the short time course (k ~0.03 min-1).
Figure S4.
Final vesicle diameter after shrinking using micelles composed of varying mole
percentages of POPC and MA, measured by DLS (~40 mM vesicles + 40 mM micelles).
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Figure S5.
The fluorescence of calcein encapsulated in MA vesicles after dilution into an isotonic
solution (0.2 M bicine, pH 8.5; brown line) or hypertonic solution (0.5 M bicine, pH 8.5;
red line). In hypertonic solution, vesicles shrink osmotically, causing the internal
concentration of calcein to increase and therefore the fluorescence to become selfquenched.1,2 The recovery of fluorescence within several hours indicates the return to a
spherical volume, due to equilibration of bicine across the vesicle membrane.
Figure S6.
Shrinking of oleate vesicles (~3 mM) after adding MA/POPC (89% MA, 11% POPC)
micelles (4 mM).
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Supplementary Text
During vesicle growth, MA micelles that are not closely associated with a membrane
(i.e., excess beyond 0.4 equivalents) aggregate into large metastable structures. However,
during vesicle shrinking, because MA/POPC micelles do not aggregate at pH 8.5, excess
MA/POPC micelles would increase the effective ratio of micelles to vesicles. Transfer of
MA from vesicles to micelles may then occur in these complexes, a first-order process
that would give rise to the observed exponential decay during shrinking.
Supplementary References
(1)
6004-6008.
(2)
5718.
Sacerdote, M. G.; Szostak, J. W. Proc Natl Acad Sci U S A 2005, 102,
Chen, P. Y.; Pearce, D.; Verkman, A. S. Biochemistry 1988, 27, 5713-
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